diff --git a/bin/ikarus b/bin/ikarus
index 36b5f12..e112280 100755
Binary files a/bin/ikarus and b/bin/ikarus differ
diff --git a/bin/ikarus-runtime.c b/bin/ikarus-runtime.c
index c42e671..5a8cd35 100644
--- a/bin/ikarus-runtime.c
+++ b/bin/ikarus-runtime.c
@@ -575,7 +575,13 @@ ERRORS
 */
 ikp 
 ikrt_file_exists(ikp filename){
-  char* str = string_data(filename);
+  char* str;
+  if(tagof(filename) == bytevector_tag){
+    str = (char*)filename + off_bytevector_data;
+  } else {
+    fprintf(stderr, "bug in ikrt_file_exists\n");
+    exit(-1);
+  }
   struct stat sb;
   int st = stat(str, &sb);
   if(st == 0){
diff --git a/src/ikarus.boot b/src/ikarus.boot
index 44606a2..63945cc 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.posix.ss b/src/ikarus.posix.ss
index 03dda6c..519ace9 100644
--- a/src/ikarus.posix.ss
+++ b/src/ikarus.posix.ss
@@ -40,7 +40,8 @@
     (lambda (x)
       (unless (string? x)
         (error 'file-exists? "filename ~s is not a string" x))
-      (let ([v (foreign-call "ikrt_file_exists" x)])
+      (let ([v (foreign-call "ikrt_file_exists" 
+                  (string->utf8-bytevector x))])
         (cond
           [(boolean? v) v]
           [else